Need help with exponential equation

Hello,

I have a job interview tomorrow, where I will be given a maths test. It's been several years since I did maths last and I'm quite rusty. I'm having difficulty with the following problem in the practice paper:

My attempt went as follows:

ln e ^ (2x) + ln 2 e ^ x = ln 8

ln 2 e ^ (3x) = ln 8

2 e ^ (3x) = 8

e ^ (3x) = 4

3x = ln 4

x = (ln 4)/3

However when I substitute this back in, it doesn't seem to work. Where am I going wrong?